I am upgrading w3-total-cache from a previous version to 0.9.1.1 and I'm getting fatal errors when I try to enable the new version. The message is:

Plugin could not be activated because it triggered a fatal error.
wp-content/uploads could not be created, please run following command:
chmod 777 wp-content

The problem is that my wp-content and wp-content/uploads folders are both 777 already! I've double-checked this on the server. Since I had no troubles running the previous version of the plugin, could the problem lie elsewhere?